1. Field of the Invention
The present invention relates to a method and apparatus for manufacturing emitter electrodes, as needle-shaped materials, to be mounted on a microemitter (electric field emitting element) constituting, for example, one kind of vacuum element and further to a method for manufacturing a microemitter as set out above.
2. Description of the Related Art
Conventionally, research has been made into a vacuum element with a vacuum used as a carrier transportation medium. A microemitter is known as one such vacuum element. As a method for manufacturing such a micro-emitter, use is made of a method for performing a fine working on it using an etching process or a method for effecting an oblique-incident type deposition of a film forming material by virtue of sputtering.
A Spint- or wedge-type is known as a typical microemitter. In the case of the Spint-type, the emitter electrode assumes a square-pyramidal or conical configuration. In the manufacture of the Spint-type microemitter, a Si substrate is anisotropically or isotropically etched using a square or circular resist mask.
In the Spint-type microemitter, on the other hand, individual emitter electrodes have sharper forward ends than in the wedge-type microemitter, but it is not easy to sharpen the individual emitter electrodes uniformly because it is difficult to set the etching conditions under which a plurality of emitter electrodes are uniformly etched.
Further, the smaller the apex angle of the emitter electrode, the more effectively an emission current is emitted. In the case where the emitter electrode is manufactured using the anisotropic etching, it is not possible to freely sharpen the emitter electrode because the apex angle is determined in its face-orientation position. It is also difficult to control the apex angle when the emitter electrode is manufactured using the isotropic etching.
In the wedge-type microemitter, on the other hand, the sharpening of the apex depends upon the accuracy with which patterning is performed with an etching mask (for example, a resist mask). Therefore, the sharpening of the apex is restricted by the resolution of a patterning device.